1. Field of the Invention
The field of the invention is related to atomizers and in particular to a fuel atomizer for an electronically controlled single point fuel injection system for an internal combustion engine.
2. Prior Art
Proper atomization of the fuel prior to being burned in an internal combustion engine, furnace, or any other liquid fuel consuming device is considered necessary for obtaining the maximum efficiency of the combustion process. Almost every imaginable mechanism known has been used at one time or another in order to achieve or improve fuel atomization. These range from swirling the fuel as taught by Delaunay-Belleville in U.S. Pat. No. 1,206,978 (December, 1916) and Grundman et al in U.S. Pat. No. 3,477,647 (November, 1969). Alternatively, Betteson in U.S. Pat. No. 2,719,056 (September, 1955); Romann et al in U.S. Pat. No. 3,680,794 (August, 1972) and Boltz et al in U.S. Pat. No. 3,782,639 (January, 1974) teach swirling the air to achieve the same purpose. It is noted that in the Romann and Boltz patents the initial atomization of the fuel is provided by nozzle configuration of a fuel injector valve which is assisted by the swirling air.
Another technique also used is to inject the fuel through a plurality of small orifices as taught by Fush in U.S. Pat. No. 1,081,228 (December, 1913) or Harper in U.S. Pat. No. 2,382,151 (Aug. 14, 1945) and maybe others. Alternately, the fuel may be dispersed using a flanged pintle for dispersing the fuel radially as it is being ejected from a nozzle as taught by Krauss in U.S. Pat. No. 3,613,998 (October, 1971) or Schlagmuller et al in U.S. Pat. No. 3,967,597 (July, 1967). Ray in U.S. Pat. No. 2,557,514 (June, 1951) teaches splashing the injected fuel against a dispersion surface. This surface may be a rigid surface as taught by Ray or may be a surface vibrating at ultrasonic frequencies as taught elsewhere in the art. It is even known to use ultrasonic sound waves themselves to atomize the fuel particles. In general, most of the above discussed methods are capable of atomizing the fuel to a greater or lesser extent and are quite satisfactory when used with a continuous fuel supply. With the advent of modern fuel control systems using computers; electronic, mechanical, hydraulic, or hybreds thereof, it has been found to be more expedient and efficient to compute and supply the engine's fuel requirements on a pulse rather than a continuous flow basis. These fuel pulses are normally produced in synchronization with the opening of the engine's individual intake valves. In a conventional multipoint injection system having one fuel injector valve for each cylinder, each valve opens only once for every two revolutions of the engine; however, in a single point fuel injection system, having only one fuel injector valve, the repetition rate of the single injector valve increases in proportion to the number of engine cylinders. In general the repetition rate of the injector valve in a single point fuel injection system increases by a factor of two to four over the repetition rate of the fuel injectors in a multipoint fuel injection system. Thus, the injector valve life expectancy in terms of vehicle mileage is reduced one-half to one-fourth the life expectancy of the same valve in a multipoint system. Another factor to be considered is the uniformity of the fuel delivery at low engine speeds. The fuel from the single injector valve is delivered at a location remote from the engine's intake ports and due to the compressibility of the air in the intake manifold the air flow at the point of injection is relatively continuous. At low engine speeds the fuel pulses are relatively short with a much longer time between pulses. At idle engine speeds the ratio of periods between injection to injection time may be as high as 10 to 1. Therefore, the intermittently injected fuel results in a stratified nonuniform air fuel mixture being supplied to the engine. At high speeds, the fuel requirements of the engine increase and the injection pulses become much longer and as a consequence the off time between injection pulses becomes inadequate for the proper opening and closing of the injector valve, and the actual fuel delivery is no longer equal to the computed value. This coupled with the decrease in the life expectancy of the injector valve has made the single point injection system unattractive to the automotive industry.
The disclosed invention is an air assisted fuel atomizer for an internal combustion engine single point fuel injection system overcoming the deficiencies of the prior art. The associated fuel control valve may supply fuel on a continuous or pulsed basis and may be either mechanically or hydraulically actuated as well as electrically actuated as shown in the preferred embodiment.